Plasma burner operated by means of gaseous mixtures

Abstract

The present invention relates to a plasma burner for metallurgical furnaces which is operated with gaseous mixtures, wherein an addition gas is fed to the plasma burner via a ring conduit into the inside of the burner. The gas conduction pipes on the addition-gas outlet are arranged at a predetermined angle to the longitudinal axis of the burner, 35° to 45°. The point of intersection between plasma arc and addition gas is 25 to 45 mm in front of the rod-shaped cathode. In order to increase the output with constant arc current and without chemical reaction with as molten material, hydrogen or nitrogen is used as addition gas; and when a chemical reaction is desired, oxygen or oxygen-containing gas mixtures are used.

We claim: 
     
       1. A plasma burner operable with gaseous mixtures for the melting of metals and alloys, comprising: a tubular body having means forming a cylindrical nozzle opening at one end and receptive of a supply of gas; a longitudinally extending rod-like cathode extending through and protruding outwardly of the nozzle opening and configured to form a cylindrical annular passage therearound which directs the nozzle flow outwardly of the tubular body and parallel to the cylindrical surface of the cathode; a ring conduit at the other end of the tubular body and receptive of a supply of an addition gas; a plurality of gas conduction pipes connected at one end to the ring conduit, extending longitudinally within the tubular body along the entire length of the tubular body and opening at said one end symmetrically on a pitch circle around the nozzle opening at an angle of from 35° to 45° with respect to the longitudinal axis of the tubular body and configured to position the point of intersection of the nozzle flow and the addition gas flow at 25 to 45 mm from the end of the cathode protruding out of the nozzle opening. 
     
     
       2. The plasma burner according to claim 1, wherein the addition gas comprises molecular gases which do not chemically react with the melt and which are selected from the group of hydrogen and nitrogen. 
     
     
       3. The plasma burner according to claim 1, wherein the addition gas comprises gases which chemically react with the melt and which are selected from the group of oxygen and oxygen contaning gaseous mixtures. 
     
     
       4. The plasma burner according to claim 1, further comprising insert members in the addition gas conduit openings to effect a higher addition gas exit velocity.